The antibacterial activity of new cephem antibiotics against clinical isolates. A comparison of the antibacterial activity of cefotaxime with 6 other antibiotics

During the period from May through July 1981, a comparative study was carried out on the antibacterial activities of cefotaxime (CTX) and ceftizoxime (CZX), cefoperazone (CPZ), latamoxef (LMOX), cefotiam (CTM), cefmetazole (CMZ) and cefazolin (CEZ). CTX and these other cephem antibiotics were tested against fresh clinical isolates which had been obtained from clinical materials by the laboratories of 14 participating medical institutions. 1. The clinical isolates were obtained from various clinical materials in the following decreasing order: urine, sputum and pus/discharge; 85.7% of the isolates came from these materials. 2. Concerning the sources of each species of clinical isolates, it was found that P. aeruginosa was isolated from the greatest number -9- of different clinical materials. This was followed by E. coli and E. cloacae, each isolated from 8 different clinical materials, and C. freundii and E. aerogenes, each found in 7 different clinical materials. 3. In relation to S. pyogenes, S. agalactiae and S. pneumoniae, CTX showed the best antibacterial activity; the second most potent antibiotic was CZX. CMZ and LMOX were found to show relatively high MIC values for those species. Against S. aureus, CEZ showed the best antibacterial activity, but 3 resistant strains had MICs of greater than 100 micrograms/ml. 4. With regard to Gram-negative bacteria, CTX and CZX showed the best antibacterial activities for all of the species, except for P. aeruginosa. These were followed, in order, by LMOX and CPZ. Compared with these 4 antibiotics, CTM, CMZ and CEZ were found to have inferior antibacterial activities against these bacteria. In relation to P. aeruginosa, the peak of the MIC distribution for CPZ was 6.25 micrograms/ml, and this was the best antibacterial activity detected with the various antibiotics tested. This was followed by CTX (25 micrograms/ml) LMOX (25 micrograms/ml) and CZX (50 micrograms/ml). CTM had an MIC of 100 micrograms/ml for 1 strain, and MICs of greater than 100 micrograms/ml for all of the other strains of P. aeruginosa, indicating them to be resistant to this antibiotic. All of the strains were resistant to CMZ and CEZ, showing MICs of greater than 100 micrograms/ml. 5. For each of the tested antibiotics, no correlation was found between the MIC and the serogroup for either P. aeruginosa or S. marcescens.     

Antibacterial activity of biapenem against recent clinical isolates

Antibacterial activity of biapenem (BIPM) against clinical isolates of 8 species between 2000 and 2002 was compared with those of imipenem/cilastatin (IPM/CS), meropenem (MEPM), panipenem/betamipron (PAPM/BP) and ceftazidime (CAZ). The MICs of biapenem for Gram-positive bacteria were higher than those of IPM/CS and PAPM/BP, equal to those of MEPM and lower than those of CAZ. The MICs of BIPM for Gram-negative bacteria were higher than those of MEPM, equal to those of IPM/CS and PAPM/BP, and lower than those of CAZ. Antibacterial activity of BIPM against Pseudomonas aeruginosa was equal to those of IPM/CS and MEPM and superior to those of PAPM/BP and CAZ. In conclusion, BIPM showed broad antibacterial activity against both Gram-positive and Gram-negative clinical isolates. These results suggest that BIPM is useful for the treatment of various bacterial infections.     

Antibacterial activity of rokitamycin against fresh clinical isolates]

We obtained bacterial strains which were clinically isolated and identified from outpatients with various infections in medical institutions throughout Japan. Possible antibacterial activities of rokitamycin (RKM) were examined against these isolates. Minimum inhibitory concentrations (MICs) were determined through a comparative study with reference drugs. The results of the study are summarized as follows. 1. Resistance patterns of 400 isolates which were highly resistant to macrolides (MLs) with MIC values > 100 micrograms/ml were classified into 55 patterns. Staphylococcus spp. showed cross resistance to 14-membered ring MLs with 100% cross resistance observed between erythromycin (EM) and clarithromycin (CAM), and 85.2% between EM and oleandomycin (OL). Fewer isolates showed strong resistance to 16-membered ring MLs than to 14-membered ring MLs. Cross resistances observed among the Staphylococcus isolates were 100% between acetylmidecamycin (MDM-AC) and kitasamycin (leucomycin (LM)), 93.9% between MDM-AC and josamycin (JM), and 53.3% between MDM-AC and RKM. Streptococcus spp. and Peptococcus spp. showed very similar resistance patterns to both 14- and 16-membered ring MLs, but resistance patterns to RKM were quite different. Most of anaerobic streptococci and Bacteroides fragilis group had similar resistance patterns to 14- and 16-membered ring MLs, but in some cases a pattern similar to that of Staphylococcus spp. was observed. 2. When ML-resistant bacteria isolated during 1975 to 1980 were compared to those isolated in 1986 and 1989, it was observed that resistance of Staphylococcus aureus remained almost unchanged, that of Streptococcus pyogenes was lower in the later years than during 1975 to 1980, but that of Streptococcus pneumoniae increased. 3. Most of ML-resistances of the resistant isolates were inducible, but extents of induction varied depending on drugs tested. Strong inductions were observed when 14-membered ring MLs were used, but inductions were minimal with 16-membered ring MLs. RKM appeared to induce resistance to the least extent. From these results, it appears that the RKM is quite useful clinically even in the 1990s.     

Antibacterial activity of gentamicin against clinical isolates in pediatrics

Antibacterial activity of gentamicin (GM), along with activities of other aminoglycosides and beta-lactams, was studied against clinical isolates collected from pediatric patients during a period of May 1986-April 1987. 1. GM-resistance was noted in 22% of Staphylococcus aureus, 6% of Proteus vulgaris, 8% of Morganella morganii, 40% of Providencia spp., 6% of Enterobacter spp., 14% of Serratia marcescens, and 14% of Pseudomonas aeruginosa isolates. No GM-resistance was observed with isolates of Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. 2. The antibacterial activity of GM against clinical isolates from pediatric patients was found to be comparable to its activity against clinical isolates from adults studied at the same time. 3. The majority of GM-resistant strains of S. aureus were MCRSA, and the GM-resistant strains of S. marcescens and P. aeruginosa were found also to be resistant to multiple drugs. 4. GM-resistant strains were found at relatively high rates (14-22%) in S. aureus, S. marcescens and P. aeruginosa. These rates did not increase compared to the rates observed in the first half of the 1980's. 5. GM was considered to have poor antibacterial activity against genus Providencia. It is concluded from above results that GM still maintains effective antibacterial activity against many of causative organisms of infections in both adults and children.     

Antibacterial activity of ciprofloxacin against fresh clinical isolates from superficial suppurative foci

The minimum inhibitory concentrations (MICs) of 5 drugs (ciprofloxacin (CPFX), and 4 drugs used as standard) were determined to investigate antibacterial potencies of CPFX against bacterial strains isolated in 1989 from superficial suppurative foci. The clinical isolates tested included 375 strains from 11 aerobic bacterial species, and 50 strains from 2 anerobic bacterial genera (group) for a total of 425 isolates. Interpreting MIC level distributions of these drugs as the expression of antibacterial potencies, the results are as follows. 1. When activities of new-quinolone antibiotics were tested, we found that, CPFX expressed far superior antibacterial potency to ofloxacin (OFLX) and norfloxacin (NFLX) against coagulase-negative staphylococci, Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Pseudomonas aeruginosa and Peptostreptococcus spp., although the activity of CPFX against Bacteroides fragilis group was weaker than that of OFLX, and CPFX had similar activity against Staphylococcus aureus to OFLX. 2. In comparison to beta-lactam antibiotics, CPFX was inferior to amoxicillin (AMPC) against E. faecalis and inferior to AMPC and cefaclor (CCL) against Peptostreptococcus spp. Against all other bacterial species, however, CPFX expressed superior antibacterial potency to AMPC and CCL. 3. Scattered findings of low sensitivity or resistance to CPFX were observed among the S. aureus, E. faecalis, E. faecium, P. vulgaris, M. morganii, P. aeruginosa and B. fragilis (group) species, but with an exception of E. faecium, the incidence of resistance strains was low.     

Antibacterial activity of cefmenoxime against clinical isolates. Comparative study

Antibacterial activity of cefmenoxime (CMX) against clinically isolated organisms was examined in comparison with that of 4 other antibiotics and concluded as follows: Antibacterial activity of CMX was markedly stronger than those of cefazolin (CEZ), cefmetazole, latamoxef and ampicillin against E. coli, K. pneumoniae, S. marcescens, H. influenzae, P. mirabilis and indole positive Proteus. But the MIC level of CMX against S. aureus was higher than that of CEZ.     

Antibacterial activity of norfloxacin against 1700 relatively resistant clinical isolates

A total of 1724 clinical isolates from patients with different infections were tested in vitro to determine their susceptibility to norfloxacin. Antibacterial activity of norfloxacin was compared with other drugs that were commonly used in the hospital. Of the 919 strains of Enterobacteriaceae tested, all except four isolates of Enterobacter, two of Serratia and one of Proteus were susceptible to norfloxacin. Ninety-five percent of the 199 strains of Pseudomonas aeruginosa were also inhibited by this quinolone. Brucella melitensis (81 strains) was completely susceptible to norfloxacin. All the 250 isolates of Staphylococcus aureus and coagulase-negative staphylococci were also sensitive to norfloxacin. Pseudomonads other than P.aeruginosa, Acinetobacter/Alcaligenes and group D streptococci were less sensitive to norfloxacin, with 56%, 57% and 20% respectively being inhibited by this antimicrobial agent.     

Antibacterial activity of cefpodoxime against clinical isolates in 2000 and 2001

As the post-marketing surveillance of cefpodoxime proxetil (Banan), MICs of cefpodoxime (CPDX, an active form of Banan) against 1090 clinical isolates of 22 species from 15 medical institutions all over Japan from June 2000 to March 2001 were measured using the broth microdilution method approved by the Japanese Society of Chemotherapy and compared with those of oral cephem antibacterials, cefaclor, cefdinir, cefditoren, and cefcapene. In this study, remarkable change in the activity of CPDX was observed in Streptococcus pneumoniae and Haemophilus influenzae compared with the susceptibility in the studies before Banan was launched. This cause is considered to be the increase in the incidence of the following resistant strains: penicillin-intermediate S. pneumoniae (47.3%), penicillin-resistant S. pneumoniae (PRSP, 15.1%), and beta-lactamase-negative ampicillin-resistant (BLNAR) H. influenzae (24.0%), which were scarcely isolated in 1989 when Banan was launched. Other tested drugs also exhibited low activity against these resistant strains. However, CPDX showed comparatively good activity with MIC90 of 2 micrograms/mL against PRSP. Against methicillin-susceptible Staphylococcus spp., Streptococcus pyogenes, Streptococcus agalactiae, and Moraxella catarrhalis, CPDX also showed comparatively good activity with MIC90 of < or = 4 micrograms/mL, which was almost equal to that in the studies before its marketing. Against quinolones-resistant Neisseria gonorrhoeae, CPDX showed excellent activity with MIC90 of 0.5 microgram/mL. Against members of the family Enterobacteriaceae except for Citrobacter freundii, Enterobacter spp., Proteus vulgaris, and Morganella morganii, CPDX showed good activity. However, in Escherichia coli, Klebsiella spp. Proteus spp., and Providencia spp., there are some high-resistant strains to all tested drugs including CPDX. Against Peptostreptococcus spp., MIC90 of CPDX was 8 micrograms/mL and its MIC range was widely distributed from 0.03 to 32 micrograms/mL, which were similar to those in the studies before its marketing. In this study, CPDX showed the decrease in the activity against several species as did other drugs tested, but against most of species tested, CPDX maintained good activity. Furthermore, it is necessary to pay much attention to the trend of resistant strains.     

Antibacterial activity of gatifloxacin against various fresh clinical isolates in 2002

Antibacterial activities of gatifloxacin (GFLX) and other antibacterial drugs against various fresh clinical strains (800 isolates) isolated from specimens of patients in 2002 were compared. GFLX was more active than levofloxacin and ciprofloxacin against Gram-positive bacteria such as methicillin susceptible Staphylococcus aureus and Streptococcus pneumoniae. For these isolates, clarithromycin and azithromycin were less active (MIC90; > 16- > 64 micrograms/mL), GFLX was more active than cefdinir. For Escherichia coli, Klebsiella pneumoniae, Acinetobacter species, Haemophilus influenzae and Moraxella (Branhamella) catarrhalis, three quinolones including GFLX were potently active (MIC90; < or = 0.06-0.5 microgram/mL). Pseudomonas aeruginosa isolated from urinary tract infections were resistant to three quinolones including GFLX (MIC90; 32-64 micrograms/mL), however P. aeruginosa isolated from respiratory and otolaryngological infections were more susceptible (MIC90; 0.5-2 micrograms/mL). Quinolones were less active against Neisseria gonorrhoeae as compared with the cephem antibiotics tested, but GFLX was the most active against N. gonorrhoeae among the quinolones tested. In this study, we investigated activity of GFLX against fresh clinical strains isolated early in 2002, GFLX is widely and potently active against S. aureus, S. pneumoniae and various Gram-negative bacteria.     

Antibacterial activity of panipenem against clinical isolates in 2000 and 2001

As the post-marketing surveillance of panipenem/betamipron (Carbenin), MICs of panipenem (PAPM) against 1355 clinical isolates of 28 species from 15 medical institutions all over Japan from June 2000 to March 2001 were measured using the broth microdilution method approved by the Japanese Society of Chemotherapy and compared with those of parenteral carbapenem antibacterials, imipenem (IPM) and meropenem (MEPM), and parenteral cephem antibacterials, cefozopran, cefepime, and sulbactam/cefoperazone. The activity of PAPM was comparable to that of IPM against almost all species tested. Compared with MEPM, PAPM was more active against Gram-positive bacteria and Bacteroides spp., and less active against Gram-negative bacteria. Compared with the parenteral cephems, PAPM was more active against most of species tested and its MIC ranges were narrower than those of the cephems as were those of other carbapenems. In this surveillance study, the incidence of resistance in various species were as follows: 39.3% for methicillin-resistant Staphylococcus aureus, 47.3% for penicillin-intermediate Streptococcus pneumoniae (PISP), 15.1% for penicillin-resistant S. pneumoniae (PRSP), 0.9% for extended-spectrum beta-lactamase (ESBL) producing Escherichia coli, 3.4% for ESBL producing Klebsiella pneumoniae, 19.2% for beta-lactamase producing Haemophilus influenzae, 24.0% for beta-lactamase-negative ampicillin-resistant (BLNAR) H. influenzae, and 1.0% for metallo-beta-lactamase producing Pseudomonas aeruginosa. Against these resistant strains, carbapenems including PAPM showed generally more potent activity than cephems. It was noted that PAPM showed the most potent activity against PISP and PRSP, which showed high incidence of 62.4% totally, among tested drugs. Metallo-beta-lactamase producing P. aeruginosa exhibited high resistance and BLNAR H. influenzae also exhibited low susceptibility against all tested drugs. But no remarkable change in the activity of PAPM against other species was observed in this study compared with that in the studies before the marketing of Carbenin. Furthermore, it is necessary to pay much attention to the trend of resistant strains such as PRSP, metallo-beta-lactamase producing bacteria, and BLNAR H. influenzae.     

4种β-内酰胺类抗生素对临床分离致病菌的体外抗菌活性

目的 对比研究头孢呋辛、头孢克洛、头孢噻肟和阿莫西林等4种β-内酰胺类抗生素对随机选取的临床分离致病菌的体外抗菌活性。方法 随机收集2006-2007年解放军总医院微生物科和空军总医院感染控制科分离的部分临床致病菌，采用琼脂平板稀释法测定最低抑菌浓度（MIC）。结果 头孢呋辛对金葡菌、表葡菌的敏感率分别为45％和83．33％，抗菌活性显著强于头孢克洛，对肺炎克雷伯菌、大肠埃希菌、阴沟肠杆菌及不动杆菌的敏感率分别为38．10％、30．77％、0、0，高于阿莫西林，弱于头孢噻肟。结论 第二代头孢菌素目前对大部分革兰阳性菌仍具有较强的抗菌活性，但对革兰阴性菌的抗菌活性明显弱于第三代头孢菌素。     

Antibacterial activity of 16 antibiotics against Helicobacter pylori

The susceptibilities of 24 Helicobacter pylori isolates, which were originated from clinical materials, to 5 beta-lactam antibiotics [benzylpenicillin (PCG), ampicillin (ABPC), cephalothin (CET), ceftazidime (CAZ), cefotiam (CTM) and imipenem (IPM)], two macrolides [clarithromycin (CAM) and rokitamycin (RKM)], two aminoglycosides [amikacin (AMK) and gentamicin (GM)], two new quinolones [ciprofloxacin (CPFX) and levofloxacin (LVFX)], two tetracycline [tetracycline (TC) and minocycline (MINO)], rifampicin (RIF) and chloramphenicol (CP) were tested. All of the isolates showed similar susceptibilities against beta-lactam antibiotics. However, MICs of CTM and CAZ were two- to four-fold higher than those of PCG, ABPC, CET and IPM, MICs of rokitamycin for the tested strains were higher than those of clarithromycin. MICs of CPFX and LVFX showed two-modal distributions. The first peak of distributions was observed between 0.06 to 0.5 microgram/ml and second one was between 4 to 16 micrograms/ml. These distributions suggested that MIC values of 4 to 16 micrograms/ml could result from the expression of a resistance mechanism. In addition, some of H. pylori strains were observed drug resistances between CP and AMK, new quinolones and AMK respectively. From the molecular epidemiological study, cryptic plasmids were detected from the 3 isolates among 24 strains tested.     

In vitro antimicrobial activity of various antibiotics against Haemophilus influenzae isolated from clinical specimens in 1983

In vitro susceptibilities of 73 strains of Haemophilus influenzae isolated from clinical specimens in 1983 to various antibiotics were studied. The following antibiotics were evaluated; ampicillin (ABPC), piperacillin (PIPC), cefotaxime (CTX), cefoperazone (CPZ), ceftizoxime (CZX), cefmenoxime (CMX), latamoxef (LMOX), tetracycline (TC), doxycycline (DOXY), minocycline (MINO), chloramphenicol (CP) and erythromycin (EM). Susceptible strains to ABPC and PIPC with MICs less than 3 micrograms/ml were 80.3 and 84.1%, respectively. With this break point of MIC, all strains showed susceptibility to CPZ, CZX, and CMX, but resistant strains were observed in 1.5% against CTX and LMOX. Susceptible strains to TC, DOXY and MINO at MICs less than 2 micrograms/ml were 86.3, 80, and 87.7%, respectively. Those to CP at MICs less than or equal to 4 micrograms/ml and to EM at MICs less than or equal to 1 microgram/ml were 86.2 and 71.9%.     

碳青霉烯类抗生素对铜绿假单胞菌抗菌活性的检测

目的 探讨铜绿假单胞菌(PA)临床分离株对碳青霉烯类抗生素耐药性与其产AmpCβ内酰胺酶(AmpC酶)的关系.方法 收集并鉴定PA临床分离株,采用头孢西丁敏感试验对产AmpC酶的菌株进行初筛.运用Kirby-Bauer纸片扩散法、固体培养基连续稀释法检测头孢菌素类与碳素霉烯类抗生素对PA筛选菌株的抗菌活性.采用三维确认试验检测碳青霉烯类抗生素耐药菌株产生AmpC酶的情况.结果 PA筛选菌株对头孢呋肟钠(CXM)、头孢噻甲羧肟(CAZ)、头孢噻肟钠(CTX)、头孢哌酮钠(CFP)及盐酸头孢吡肟(FEP)的耐药率分别为100%、36.3%、63.6%、54.5%、22.7%;对亚胺培南(IPM)、帕尼培南(ETP)、美罗培南(MEM)的耐药率分别为40.9%、45.0%、18.1%,部分菌株对所有试验用药均耐药.IPM、ETP、MEM对PA筛选菌株的最低抑菌浓度(MIC)均≥19 μg/ml,且各试药的最低杀菌浓度(MBC)值与MIC值相差较大,约36.0%菌株的MBC是MIC的16～32倍.约22.6%菌株检测出产生AmpC酶.结论 我市医院近半年来收集的PA对第4代头孢菌素类抗生素FEP具有较高的敏感性;对临床用碳青毒烯类抗生素MEM的敏感性明显高于IPM与ETP,但有较大比例的耐药菌株出现;部分菌株耐药性形成可能与其产生AmpC酶有关系.     

Antibacterial activity of cefotiam against clinical isolates in the field of obstetrics and gynecology

Antibacterial activity of cefotiam (CTM) against clinically isolated organisms in the field of obstetrics and gynecology was discussed as follows: In the point of view of the MICs peak, CTM was 1-fold worse than CEZ against Gram-positive bacteria, while, in the case of the concentration of CTM required to inhibit the growth of 80% or 90% of the total number of tested Gram-positive organism, antibacterial activity of CTM was approximately identical with that of CEZ, CMZ or SBPC. CTM against E. coli, K, pneumoniae, P. Mirabilis was 16-32-fold more effective than CEZ and 4-16-fold than CMZ. Against indole-positive organisms with CEZ was no effective, CTM was considerably effective. But antibacterial activity of CTM against B. fragilis was insufficient. However, in the case that no spore forming anaerobic organism involved in infectious disease, it is said that existence of aerobic organism is important. As E. coli is representative of aerobic organism, CTM with potent antibacterial activity against this organism is seemed to be effective antibiotic for the gynecological infection.     

Antibacterial activities of monobactams against fresh clinical isolates

Antibacterial activities of monobactam antibiotics (carumonam (CRMN) and aztreonam (AZT] against Gram-negative bacilli isolated from inpatients in the latter half of 1987 were investigated using penicillin (PC: piperacillin (PIPC], cephems (CEPs: ceftazidime (CAZ), cefotaxime (CTX), latamoxef (LMOX), cefsulodin (CFS], carbapenem (imipenem (IPM] and pyridonecarboxylic acids (norfloxacin (NFLX) and ofloxacin (OFLX] as reference antibiotics. A total of 400 strains of 13 species, i.e. Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Providencia rettgeri, Citrobacter freundii, Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, Pseudomonas aeruginosa and Haemophilus influenzae, were used as test strains. 1. CRMN and AZT, both monobactam antibiotics, were roughly comparable in their activities and no resistant strain to these antibiotics were found among isolates of E. coli, Klebsiella spp., Proteus spp., M. morganii, P. rettgeri or H. influenzae and few resistant strains were observed among isolates of S. marcescens. On the other hand, isolates of C. freundii, Enterobacter spp. and P. aeruginosa included rather numerous strains resistant to the monobactam antibiotics. Among these cases, whereas R strains, i.e. resistant strains showing MICs greater than or equal to 50 micrograms/ml, accounted for a large proportion of strains resistant to PC and CEPs, I strains, i.e. intermediately resistant strains showing MICs between 12.5 and 25 micrograms/ml, accounted for a large proportion of strains resistant to the monobactam antibiotics. 2. Strains resistant to PIPC, a PC, were detected with high and more or less uniform frequencies over the entire spectrum of the isolates examined. 3. Antibacterial activities of CEPs varied against different bacterial species. While strains resistant to CTX, CAZ and LMOX were commonly detected with high frequencies among isolates of C. freundii, Enterobacter spp. and S. marcescens, large percentages of LMOX-resistant strains of C. freundii and Enterobacter spp. were of the I type. CTX-resistant strains were also found among isolates of P. vulgaris and M. morganii. Proportions of CEP-resistant strains of P. aeruginosa were 28% for CFS and 12% for CAZ. 4. No or few strains among the isolates of 13 species investigated were resistant to IPM, a carbapenem antibiotic, which showed the most stable antibacterial activity, but it was less active than monobactam antibiotics and CEPs against Klebsiella spp., P. mirabilis and H. influenzae.(ABSTRACT TRUNCATED AT 400 WORDS)     

Sensitivity of the recent bacterial isolates to cefotaxime and other cephem antibiotics

Antimicrobial susceptibility of 703 nonselected strains of 14 different bacterial species to cefazolin, cefmetazole, cefotiam, cefoperazone latamoxef, and cefotaxime (CTX) was examined. CTX was the most active against E. coli, Klebsiella, Serratia, P. mirabilis, H. influenzae, beta-Streptococcus group A, beta-Streptococcus group B and S. pneumoniae. On the other hand, CTX-resistant (MIC greater than or equal to 50 micrograms/ml) strains were isolated at the following frequencies: Citrobacter, 21.7%; Enterobacter, 7.7%; Serratia, 4.6%; P. aeruginosa, 40.4% and B. fragilis, 28.6%. Of the 411 strains classified as very sensitive () or moderately sensitive (++) by disk method, 405 strains (98.5%) were inhibited by less than or equal to 12.5 micrograms/ml of CTX. Only 1 strain (0.2%) was falsely classified as moderately sensitive and no strains were falsely categorized as resistant.     

Antibacterial activity of moxalactam (LY-127935) compared with cefotaxime and other beta-lactam antibiotics against clinical isolates of enterobacteriacea and non-fermenters

The in vitro activity of moxalactam, a new semisynthetic 1-oxa-beta-lactam, was compared to those cefotaxime, cefuroxime, cephalothin, piperacillin and tobramycin against more than 500 clinical isolates of Enterobacteriaceae and non-fermenters. The geometric mean MIC against 450 Enterobacteriaceae in microgram/ml was 0.09 for moxalactam, 0.08 for cefotaxime, 5.3 for cefuroxime, 22.9 for cephalothin, 3.5 for piperacillin and 0.72 for tobramycin. The geometric mean MIC in microgram/ml against 60 P. aeruginosa strains was 12.7 for moxalactam, 22.9 for cefotaxime, 6.8 for piperacillin, 1.5 for tobramycin and 2.9 for cefsoludin. The minimum inhibitory and the bactericidal concentrations of moxalactam were almost the same in most species. The effect of the inoculum on the bactericidal concentration was slight, between 10(3) and 10(7) CFU/ml for the E. coli and the Klebsiella strains. In isolates of S. marcescens and P. aeruginosa the bactericidal concentrations increased by 4 to 5 log2 and in isolates of P. mirabilis the increased by 9 log2 with the largest inoculum.     

Antibacterial activities of sisomicin against fresh clinical isolates]

To investigate antibacterial activities of sisomicin (SISO), MICs of SISO as well as other aminoglycosides (AGs) were determined against many clinical isolates which were obtained in 1991. Results are summarized below: 1. No SISO-resistant strains were observed among isolates of Escherichia coli, Citrobacter diversus, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Proteus mirabilis and Morganella morganii. 2. In comparison with the results of our previous study against isolates obtained in 1986, the rate of methicillin-resistant Staphylococcus aureus (MRSA) was higher, and SISO-resistant strains were observed at a high rate among the MRSA. Also, SISO-resistant strains of Serratia marcescens increased. However, the rate of SISO-resistant strains of Pseudomonas aeruginosa decreased, and among Citrobacter freundii, Enterobacter cloacae and Proteus vulgaris, SISO-resistant strains did not increase over the years. 3. MICs of SISO against Providencia rettgeri and Providencia stuartii were high, suggesting that antibacterial activities of SISO was weak against genus Providencia. 4. For comparison, according to MICs of ofloxacin and imipenem, new quinolone-resistant strains were observed at a high rate among various organisms, and carbapenem-resistant strains were observed at a high rate among S. marcescens and P. aeruginosa. 5. SISO is still one of the useful AGs in the 1990's since it maintains its strong antibacterial activities against most clinical isolates obtained in recent years and its potential as a combination drug with beta-lactams is being reported.